Home |
Search |
Today's Posts |
#1
![]() |
|||
|
|||
![]()
Ok guys, put on your thinking caps. This should be fun and a wonderful
learning experience for alot of people, particuarly myself ![]() I've got a Cobra 19XS that I've had for quite some time. It hasn't worked since it was given to me by my father. I thought it would be fun to try and get it working again for no other reason than "I've got nothing better to do". It'll be cool. The radio lights up, but has no RX or TX. If you crank the volume, you can hear a very slight hissing sound with your ear up against an external speaker. REAL quiet. Attemping to transmit illuminates the TX light, but alas...no carrier. Connecting the RF siggen to the antenna terminal doesn't help. I'm having trouble tracing the signal back from the antenna based solely on the schematic I've obtained (purely a skill/experience issue). I suspect there's a problem in the PLL synthesizer circuit, as a failure here would make the radio behave as observed. There could be other things wrong, I'm sure. The only data I've been able to obtain on the radio thus far is a schematic from cbtricks.com. It's helpful, but I don't have the skills necessary to identify various circuits in the radio or determine proper test points based on the schematic alone. A service manual would be nice, but I don't have one. This is where some of you REAL techs might help me understand things a little better. I can't tell what voltages/frequencies/etc to examine at what points based soley on the schematic. Perhaps some of you can? I do have the data on the PLL (Sanyo LC7131). I do have some nifty equipment available to help us troubleshoot this at this very moment on my bench: 1.) 8 digit benchtop frequency counter (10Hz - 2.4Ghz) 2.) BK Precision RF Signal Generator model 2005 (100KHz - 150MHz, Internal 1KHz audio gen, provisions for external audio gen, variable RF and Mod levels, provisions for external FREQ. counter). Checked this with my freq counter, and it's suprisingly stable. 3.) Fluke 8060A DVM. (It's old, but it works!) 4.) Soldering goodies. The schematic is available he http://www.cbtricks.com/Cobra/19xs/cobra_19xs_sch.pdf I don't have a scope available at the moment, though I'll be purchasing one shortly. If I NEED any additional equipment to get this radio working and/or provide feedback to your questions I'll purchase it. I want this to be a fun learning experience. That being said, let's start troubleshooting! This is what this group is all about. ![]() -- Alan Strawinski http://alan.strawinski.net |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
WANTED: Cobra SR-15 handheld scanner | Equipment | |||
WANTED: Cobra SR-15 handheld scanner | Equipment | |||
WTB COBRA 66 LTD | CB | |||
cobra 29 with sound tracker,,doesnt hear good,,schematic?? | CB | |||
FA** Cobra 2000GTL W/extras | CB |